• Bright, flirty and fun – marigolds are one of the easiest seeds to sow. Find a sunny place to scatter the seeds. Cover them with a fine layer of soil and water gently for the first week to two, making sure that the soil does not dry out. If you have planted the seeds too closely, thin the seedling out when they are about 4 to 6cm high. Marigolds are great companion plants in veggie gardens.